Thursday, May 24, 2012

Revit Family Formula Examples and Tricks

Revit Family Formula Examples and Tricks

When creating formulas in a family it is helpful to have a go to list of examples. Here is mine.

IF StatementIF (Length < 30′, 2′ 6″, 4′) If the Length parameter is less than 30' x = 1 , y = 22'-6" If the Length parameter is greater than 30' this parameter will have a value of 4'-0"

IF that Returns a StringIF (Height > 30′, “This thing is tall”, “This thing is short”) If the Height parameter is greater than 30' this parameter will return This thing is tall If the Height parameter is less than 30' this parameter will return This thing is shortNested IF StatementsIF (Length < 35’, 2′ 6″ , IF (Length < 45′, 3′ , IF (Length < 55′, 5′, 8′ ) ) ) If Length is less than 35', this parameter will have a value of 2'-6" If Length is between 35' and 45', this parameter will have a value of 3' If Length is between 45' and 55', this parameter will have a value of 5' If Length is greater than 55', this parameter will have a value of 8'

IF applied to a Yes/No conditionLength > 40' If Length is greater than 40' the the statement is true and the Yes/No check box is checked If Length is 40' or less the statement is false and the Yes/No check box is NOT checked

IF ORIF (OR (A = 1 , B = 3 ) , 10 , 5) If A = 1 or B = 3 this parameter will have a value of 10 If A is not = 1 and B is not = 3 this parameter will have a value of 5

By specifing that metal can not be true while Wood is true the user can only specify one of the two materials. They both can not be checked at the same time. This can be used for visibility where a left or right access panel may be required but never both.

Pick One and Only One

Here the condtion number will allow only one paramter to be true in a list.﻿ Associated with a type, you could control a ton of things simply back picking the correct type.

"Don't Change Me Bro"

If you need some text to not change, put that text in the Formula column with quotes around it. It greys it out in the Value column. This should stop the majority of users from changing its value.

Swapping Nested FamiliesIn a bookcase family with a nested shelf family, follow these steps to add a parameter that will allow the user to switch from one type of shelf to another.

1. Open the original shelf family and save it as the second shelf option. Add something to make it different.

2. Load this new shelf into the bookcase family, but do not place it.

3. In the Family Types dialog create a new Type parameter named “Swappable Shelf”. Make its discipline Common, its Type of Parameter and group it under Constraints.

4. When you select the Type of Parameter Revit will open the Select Category dialog. Pick Generic Models.

5. Select the original shelf in the bookcase family now. In the Properties dialog, look for the Label parameter and change it to “Swappable Shelf”.